不同前处理方法对原子荧光法测定食品中总砷结果的影响

目的了解不同前处理方法对原子荧光法测定食品中总砷结果的影响。方法对氢化物-原子荧光法测定食品中总砷的前处理方法进行研究,探讨干法灰化法、湿法消解法、微波消解法、硝酸预处理-干灰化法4种前处理方法对原子荧光法测定食品中总砷测定结果的影响。结果在最佳条件下,分析方法的RSD为1.2%~3.8%(n=11),线性范围为0~150μg/L,相关系数r=0.999 9;在取样量为2.0g时,方法的检出限为0.004 7mg/kg。结论硝酸预处理-干灰化法适用于食品特别是富含有机砷的食品中总砷的测定,传统干灰化法、微波消解和湿消解法适用于样品中砷存在形式比较简单的食品样品。     

微波消解-氢化物发生原子荧光光度法测食品中总砷

目的利用微波消解—氢化物发生原子荧光光度法测定食品中总砷。方法试样采用硝酸微波消解,用氢化物发生原子荧光光度法测定食品中总砷。结果方法检出限0.002 mg/kg,测定精密度为1.0%和1.2%,回收率在95.9%～103.2%之间。结论方法快速,准确,可靠,满足食品中总砷的测定。     

对海鱼粉中总砷含量的不同消解、检测方法对比探讨

目的对国家食品安全风险评估中心下发的HMRL1601海鱼粉质控样品中总砷含量进行测定,探讨最优检测方法。方法对国家标准方法推荐的电感耦合等离子体质谱法、原子荧光法的前处理条件进行优化,使用优化后的最佳条件检测并进行比对。结果采用原子荧光法检测总砷时,湿法消解比微波消解前处理效果好,而在使用湿法消解-AFS法时,采用硝酸-高氯酸-硫酸体系消解效果好;对于电感耦合等离子体质谱法测定样品中的总砷,微波消解比压力罐消解前处理效果好;2种方法进行比较时,微波消解-电感耦合等离子体质谱法测定的海鱼粉中总砷含量较为准确,而湿法消解-原子荧光法检测的结果相对偏低。结论相较于湿法消解-原子荧光法,微波消解-电感耦合等离子体质谱法更适合测定海鱼粉类有机砷含量较高的样品。     

原子荧光法中微波消解、干灰化前处理法测定食品中总砷的结果对比

目的建立准确、可靠、稳定的方法测定食品中总砷的分析方法。方法利用干灰化法和微波消解法分别处理食品样品,对样品分析的最佳消解条件进行探讨,同时优化检测条件,用氢化物发生-原子荧光光谱法测定食品中总砷的含量。结果最佳检测条件:还原剂硼氢化钾的浓度为2.0%,灯电流为60 m A,载气流量为400 ml/min,载流为5%的盐酸,砷的浓度在0.00μg/L~50.00μg/L线性关系良好,相关系数为0.999 7,检出限为0.048μg/L。采用国家标准物质鸡肉粉(GBW 10018)和大米粉(GBW 10010)进行方法验证,所测结果均在标准参考值范围内,6次平行测定的相对标准偏差≤2.70%。结论微波消解法耗费时间短,但酸的用量大,适合砷存在形态相对简单的样品;干灰化法耗费时间较长,适用于挥发温度高、油脂含量高、砷存在形态比较复杂的样品。氢化物发生原子荧光光谱法准确、灵敏、简便高效,适用于食品中总砷含量的测定。     

微波消解法与湿法消解法在测定食品总砷中的比较

目的探讨微波消解法和湿法消解法在前处理食品(米粉和麦粉)中对食品总砷含量测定结果的影响。方法根据国家标准GB 5009.11-2014总砷中第二法(氢化物发生原子荧光光谱法),分别采用微波消解与湿法消解法对质控样品和试样样品消解处理后进行总砷含量测定。结果两种处理方法测定食品(米粉和麦粉)中总砷,其含量为0.726 mg/kg时,两法精密度、准确度都较高(RSD2%,回收率为112%115%),试样样品检测结果差异无统计学意义(t=0.723,P0.05);在总砷含量为0.317 mg/kg时,湿法消化检测结果准确性很高(RSD2%,用"z-比分数"法对测试结果进行评价,z值均≤2),而用微波消解法检出总砷含量为0.222 mg/Kg,仅为质控样品含量的70%(RSD=2.8%),内质控样品两种方法检测结果差异有统计学意义(t=7.491,P0.05)。国标规定,谷物中总砷含量限值为0.5 mg/kg,本次试验以此值为分界值,低于0.5 mg/kg的样品称为总砷含量较低的样品,而高于0.5 mg/kg的样品称为总砷含量较高的样品。结论微波消解法和湿法在消解麦粉和米粉样品时,总砷含量高,两种方法测定结果一致性好。样品总砷含量低时,湿法消解处理待测样品,检测结果可靠。     

微波消解原子荧光法测定食品中的砷

目的：建立测定食品中砷的微波消解原子荧光法。方法：采用微波消解处理样品，原子荧光法分析测定。结果：砷标准系列浓度在0～8．0ng／ml范围内线性关系良好。本方法检出限为0．11ng／ml，样品中砷回收率为88．0％．93.2％，具有简便、快速、灵敏、准确的特点。结论：本方法测定结果令人满意，具有一定的实用价值。     

大米粉中总砷含量测定的前处理方法探讨

目的 探讨微波消解过程添加过氧化氢对大米粉中总砷含量测定结果的影响.方法 参照国家标准GB 5009.11-2014总砷的测定方法,通过添加过氧化氢进行微波消解前处理样品,检测样品来自大米粉总砷含量的内质控样,分别采用电感耦合等离子体质谱法(ICP-MS)和原子荧光光谱法(AFS),测定样品中总砷含量.结果 通过微波消解法消解样品,ICP-MS法测定样品中总砷含量,非过氧化氢组测定结果为(0.386±0.030)mg/kg,过氧化氢组测定结果为(0.355±0.022)mg/kg,两组测定结果的差异有统计学意义(t = 6.293,P＜0.05);AFS法测定样品,非过氧化氢组测定结果为(0.284±0.002)mg/kg,过氧化氢组测定结果为(0.307±0.014)mg/kg,两组测定结果之间的差异有统计学意义(t= 8.979,P＜0.05).结论 微波消解法前处理大米粉样品,添加过氧化氢的微波消解样品,测定结果更接近指定值,结果相对准确可靠.     

一次微波消解原子荧光法测定土壤中砷汞

目的:探索测定土壤中砷汞的简便、经济、准确的方法。方法:采用一次微波法消解原子荧光法测定,并与湿法消解原子荧光法进行比较。结果:该方法线形范围砷为0~200 ng/ml,汞为0~50 ng/ml,样品检出限砷为21 ng/mg,汞为4 ng/mg,相对标准偏差砷为1.3%,汞为1.91%,适用于土壤中砷汞的快速测定。     

皮蛋中总砷含量的微波消解-原子荧光测定法

目的建立一种快速准确的微波消解-原子荧光光谱法用于皮蛋中总砷含量的测定。方法采用微波消解对样品进行前处理,以硫脲-抗坏血酸作为还原剂,应用氢化物发生—原子荧光分析技术测定皮蛋中总砷。结果通过正交设计,在优化的最佳消解和反应检测条件下,砷浓度范围在0～50μg/L内线性关系良好,相关系数为0.9996,检出限为0.048μg/L,样品的相对标准偏差(RSD)为3.0%,加标回收率为90.1%～94.5%。结论该方法简便快速,准确灵敏,适用于皮蛋中总砷含量的测定     

食品中铅和砷的微波消解-原子荧光同时测定法

目的建立同时测定食品中的铅和砷的微波消解-原子荧光光谱法。方法用微波消解法对食品进行前处理,用原子荧光光谱法同时测定铅和砷的含量。结果铅和砷在0-50 ng/m l的线性范围内,相关系数r分别为0.9992和0.999 8,方法的检出限分别为0.10和0.04 ng/m l,样品的加标回收率均在95%-98%之间,RSD为1.67%-4.41%。结论该方法样品前处理简单,快速、试剂用量少,检测结果准确度高,精密度好,能满足食品中微量铅和砷含量的测定要求。     

Calcium intake in the elderly: validation of a dietary questionnaire

Epidemiological studies of calcium and osteoporosis have been hampered by the lack of a suitable tool for assessing calcium intake. This report describes a new frequency and amount questionnaire for measuring present and past calcium intake in the elderly. The validity of the questionnaire was tested against two commonly used standards of dietary assessment, five-day duplicate diets and seven-day weighed dietary inventories. The resulting correlation coefficients were, respectively, r = 0.76 and r = 0.69, while that for repeatability was r = 0.84. Furthermore, the questionnaire categorized subjects into thirds of the distribution of intake with almost no gross misclassification. It is suggested that the present findings may be extended to the majority of normal, healthy elderly subjects, implying wide application for the questionnaire in the assessment of calcium intake in the elderly.     

Self-reported health problems among Swedish miners one year after unemployment

Unemployment is considered to be a public health concern sincedeterioration in the health of the unemployed is often anticipated.However, for some groups, such as miners, unemployment mightimprove health due to a cessation of potentially harmful occupationalexposures. This study evaluates the health of 79 miners in oneSwedish iron-ore mine, and 226 age-matched controls from thegeneral population, during one year after the closure of themine. The participants received a questionnaire regarding medicalhistory and subjective symptoms at the beginning of the studyperiod, and after one year. Statistically significant negativeeffects on self-reported health attributable to unemploymentwere not found, although neuropsychiatric symptoms were morecommon among the unemployed miners. The miners reported a statisticallysignificant improvement in grip force (p=0.031). They had asignificantly higher prevalence of symptoms associated withmining related exposures when compared with the population controls;pain in the upper extremities [relative risk (RR)=2.27, 95%confidence interval (Cl)=1.44–3.59), back pain (RR=1.84;Cl=1.237–2.75), vasospastic disease of the fingers (RR=2.05;Cl=1.18–3.57) and obstructive respiratory symptoms (attacksof dyspnea and wheezing: RR=3.67; Cl=1.167–11.6).     

Excès de cas humains et animaux de tularémie en France au cours de l’hiver 2007–2008 : émergence ou phénomène isolé ?

Context

Tularemia is a zoonosis affecting humans and hares in France. We describe the results of surveillance in both species, in 2007 and 2008.

Methods

Human tularemia cases are mandatorily notifiable in France since 2003. In hares, surveillance relies on volunteer hunter associations in all districts of the country. Data from mandatory reports and volunteer surveillance in 2007/2008 were analyzed and compared with previous results.

Results

In 2007/2008, 144 cases were reported in humans and 117 cases in hares. This was a 100% increase compared to previous years. Human cases differed from those of previous years only by the frequency of contact with breeding animals. Human cases without any documented risk exposure were also more frequent.

Conclusion

An increase of tularemia cases occurred in 2007/2008 in both species. Complementary studies are needed to identify the species reservoir in France to understand the causes of this peak of cases.     

Occupational health hazards in mining: an overview

This review article outlines the physical, chemical, biological, ergonomic and psychosocial occupational health hazards of mining and associated metallurgical processes. Mining remains an important industrial sector in many parts of the world and although substantial progress has been made in the control of occupational health hazards, there remains room for further risk reduction. This applies particularly to traumatic injury hazards, ergonomic hazards and noise. Vigilance is also required to ensure exposures to coal dust and crystalline silica remain effectively controlled.     

Manufacture and use of nanomaterials: current status in the UK and global trends

This paper provides an overview of the production and use of nanomaterials (NMs), particularly in the UK. Currently, relatively few companies in the UK are identifiable as NM manufacturers, the main emphasis being the bulk markets in metals and metal oxides, and some niche markets such as carbon nanotubes and quantum dots. NM manufacturing in the UK does not reflect the global emphasis on fullerenes, nanotubes and fibres. Some assumptions have been made about the types of NM that are likely to be imported into the UK, which currently include fullerenes, modified fullerenes and other carbon-based NMs including nanotubes. Many university departments, spin-offs and private companies have developed processes for the manufacture of NMs but may only be producing small quantities for research and development (R&D) purposes. However, some have the potential to scale up to produce large quantities. The nanotechnology industry in the UK has strong R&D backup from universities and related institutions. This review has covered R&D trends at such institutions, and appropriate information has been added to a searchable database. While several companies are including NMs in their products, only a few (e.g. manufacturers of paints, coatings, cosmetics, catalysts, polymer composites) are using nanoparticles (NPs) in any significant quantities. However, this situation is likely to change rapidly. There is a need to collect more information about exposure to NPs in both manufacturing and user scenarios. As the market grows, and as manufacturers switch from the micro- to the nanoscale, the potential for exposure will increase. More research is required to quantify any risks to workers and consumers.     

深圳公立医院管理体制改革制度设计

深圳公立医院管理体制改革实行政事分开、管办分开,在理事会架构下按法定机构模式组建市医管中心,落实公立医院运营管理自主权.作者从当前公立医院管理体制的弊端入手,介绍了深圳市进行公立医院管理体制改革的基本思路及改革方案设计的主要举措,深入剖析了的改革方案的特点,并对改革效果进行了预测.     

Effects of nitrogen dioxide on red blood cells of rats: Changes in components of red cell membranes during in vivo exposure to NO2

Red cell membranes, prepared from red blood cells of rats exposed to 4, 10, or 20 ppm nitrogen dioxide (NO₂) for 1 to 10 days, were examined for evidence of changes in membrane components. Appreciable changes were not found in contents of phospholipid and cholesterol during exposure to 10 ppm NO₂. By contrast, protein content altered with the time of exposure. Moreover, changes in protein composition were observed by employing sodium dodecyl sulfate — polyacrylamide gel electrophoresis. Twenty-four-hour exposure to NO₂ at the concentration above 10 ppm resulted in a marked increase in the percentage of lysophosphatidylethanolamine (LysoPE) to the total phospholipids. The prolonged exposure to 10 ppm NO₂ gave rise to a further increase in LysoPE, whereas the percentage of phosphatidylethanolamine (PE) showed a gradual decrease. A 1-day exposure to 4.0 ppm NO₂ also caused an increase in sialic acid content and decreases in those of PE and hexose. In addition to contents of these components the percentage of LysoPE increased 5 days after exposure and the elevated values were maintained up to the end of exposure period. These results demonstrate that red blood cells in circulation exhibit different membrane properties in terms of lipid and carbohydrate composition during 10 days of exposure to 4.0 ppm NO₂.     

Investigating clusters in the workplace and beyond

Clusters of disease are common and occur in the workplace and in the general community. They often arouse considerable concern among the population. Investigations have sometimes lead to exciting new knowledge, but in general the investigation of clusters is difficult and often unrewarding, especially for community clusters. In the workplace, investigations are more likely to find associations and even new causes, but still many clusters remain enigmatic. Despite this, there are many reasons for investigating clusters, including allaying community concern and identifying uncontrolled exposures. A structure for investigating clusters in the workplace is suggested.